1. Field of the Invention
This invention relates to a magnetic tape recorder and cartridge, and in particular, to determining certain relevant conditions of the cartridge when positioned in the recorder.
2. Description Relative to the Prior Art
It is known in the art that if a magnetic medium containing recorded information is later overwritten, the earlier stored information will be destroyed. If this occurs inadvertently, the result may be a complete loss of valuable data. For that reason, techniques have been developed to prevent unwanted erasure of the medium and such techniques are known as "write protect" features. In a reel to reel recorder, write protect is generally accomplished by removal of a plastic ring that is concentric with the reel hub. The absence of the ring is mechanically detected when the reel is mounted on the transport, and the write circuits accordingly are deactivated. Similarly in an audio cassette or data cartridge the presence or absence of either a plastic knockout or the position of a slidable tab allows a mechanical finger in the recorder to detect a write protect condition. Write protection exists when the finger motion is unimpeded as it enters the resulting void in the tape cassette or cartridge when the cassette or cartridge is inserted into the recorder. A floppy disk has a notch in the disk envelope which, when uncovered, plays a similar write protect role. Considered from the point of view of indications to the recorder itself, it will be noted that the write protect of the prior art functions to prevent recording when either there is no magnetic medium positioned in the recorder, or when the magnetic medium container has been set by the user to inhibit recording. In the prior art, write protect provides no specific indication that the magnetic medium is, in fact, in place in the recorder.